Should that happen, that would be a major shakeup for two movies that are part of franchises that thrive in the summertime. Marvel in particular is famous for snagging either the first weekend of May or, in the case of the latter two Avengers installments, the last weekend in April, for one of its movies. The Fast Furious film series, i.e. the Fast Saga, has been a little more flexible with its release dates, but with the exception of Hobbs Shaw, every movie has come out between April and June.
Article source: https://www.cinemablend.com/news/2491498/despite-box-office-concerns-black-widow-and-f9-are-likely-to-roll-out-on-time-heres-the-latest